Differential coupling arrangement



April 2, 1946. ue -:5 2,397,543

- DIFFERENTIAL COUPLING ARRANGEMENT Filed 061?. l, 1943.

INVENTOR. MORTON rue/45 BY I.

ATTORNEY Patented Apr. 2, 1946 Morton Fuchs, New York, N. Y., casino: to Federal Telephone and Radio Corporation, New York, N. Y., a corporation of Delaware Application October 1, 1943, SerialNo. 504,543

Claims.

i it is necessary in certain radio circuits to adjust the relative amounts of energy fed to several antennas from a single transmitter. The problem is complicated by the fact that in many highfrequency transmission lines such a variation in the power ratio mismatches the line and causes an unwanted change in the impedance thereof.

. der of a quarter-wavelength of the operating frequency oi the system in a manner similar to that of the transmission line portions referred to Accordingly, it is one object of the present invention to provide an improved means for coupling a single source of power to a plurality of loads so that the ratio of the power delivered to the individual loads may be readily varied.

A further object of the invention is to provide a pair of networks which are adjustably coupled to a transmissionline connecting a plurality of loads, so that a change in the position of the networks with respect to the line will vary the amount of power delivered to each load.

A still further object of the invention is to design a pair of connected networks having a pivoted connecting point, so that each of the networks may be selectively rocked into close physical relationship with a transmission line to provide a high degree of coupling therebetween. The invention also contemplates curving the outer ends of the networks so as to permit a rocking movement over a greater angle without bringing the selected network into contact with the transmission line.

An additional object of the invention is to provide an energy-fed network adjustably coupled to a transmission line, the electrical length of both the network and the line being so chosen with respect to the operating frequency that adjustment of the network relative to the line will not disturb the input impedance of the circuit feed-'- ing energy to the network.

Other objects and advantages will be apparent from the following description of a preferred form of the invention and from the drawing, in which:

Fig. 1 is a circuit diagram of a preferred trans.- mission system in accordance with the present invention; and

Fig. 2 illustrates a modification of Fig. l in which the network conductors are-of a different configuration.

In the form of the invention illustrated in Fig.

1, there is shown a pair of loads R1 and R2 connected by a transmission line having two parallel spaced-apart conductors 4, 6. Loads R1, R2 may constitute any type of current consuming devices, such for example as a pair of antennas. The transmission line 4, 6 connecting the loads R1, R2 is divided by the short-circuiting connection 8 into two, portions A and 13, each of which is in the order of'a quarter-wavelength of the operating frequency of the transmission system, as indicated in the drawing.

Coupled to the transmission line 4, 6 are two network sections C, D each of which is in the orabove. Network section C is formed of two parallel spaced conductors 9, in which have a shortcircuiting member ii at one end thereof. Network section D is similarly-formed of 'two parallel conductors l2, l3 having a short-circuiting member H. The adjacent ends of conductors 9 and I? are rigidly joined together within a pivoting member l5, and in a like manner the adjacent ends of conductors Hi and i3 are rigidly joined together within a pivoting member It. An insulating shaft ll? connects the pivoting members l5, it, this shaft ll being substantially parallel with, and lying approximately above, the short-circuiting connection 8 in transmission line 4, 6. It is intended that the line and network members will be positioned so that the plane of the former will be normally parallel to the plane of the latter, with the respective conductors of each lying in parallel relation one above the other, The shaft H1 is rotatably positioned in a support l8, while a crank l9, secured to pivoting member i5 by a second shaft 20, is provided for rotating the network assembly. A source of high-frequency power E is connected to the network sections through pivoting members l5, l6 as by two flexible conductors 211 22. It should be emphasized at this point that the means herein described for pivoting and rotating the network sections is given merely by way of example, and that any other known means for performing these functions may obviously be employed in place thereof.

Upon actuation of crank l9, shaft l'l will be rotated. This rotation of shaft ll will rock one or the other of network section C, D into closer physical relationship with the transmission line to increase the coupling effect between such selected section and the line. 01 course, the same rocking action will draw the other network sec- Y tion away from the line to decrease its coupling veffect. -In all, the relative coupling between A and C, on one hand, and between'B and D, on

the other, can be varied within quite wide limits by a rocking movement or comparatively slight extent. with such an arrangement a power ratio in the order of25zl can be obtained. Due to the short-circuiting effect of connection 8, substantially no interference between the coupled membersA,CandB,Dwllloccur.

It has been stated that of the members A, B, C and D are dimensined in the order of-a quarter-wavelength of the frequency of the power produced by source E. Under such conditions the physical proportions of the various conductors, as well as the spacing therebetween, can be chosen so that, for. any values of R1 and R2, the impedance Zn of the line 2|, 22 willremainsubstantially constant regardless of the relative coup i between li -C and 3-D. Thus the rocking action of the Joined networks about pivoting members. l5, ld will not change to any appreciable degree the input impedance of the networks.

' Fig; 2'is a. modification of Fig. l in which the conductors of the quarter-wave network sections I necting the junction of said networks to said C, D 02 Fig. 1 are shown at C, D with their outer ends curved away 1'rom the transmission line, thus permitting a rocking action ofthe joined networks about pivoting members l5, It to bring one or the other of the sections into closer physical relationship with the line than would be possible with sections of the linear configuration of conductors 8', it, I 2', l 3' will depend on the electrical and physical characteristics of the system and on the degree of coupling desired.

Obviously the quarter-wave transmission line portions A, B' of Fig. 1 may be extended to any odd multiple of a quarter-wavelength without altering the electrical characteristics ,of the systei'n. It should also be noted that these line portions A, B can bermade of any length desired without regard to the frequency of the power produced by source E. Sections C. D can also be made of any suitable length, although their equaltained. While the ratio of power delivered to ioads R1, R2 may be altered as'previously described by a rocking action of. network sectionsillustrated in Fig. 1. The amount or curvature source of power, means for pivoting said joined networks at said junction point thereof, and means for selectively rocking said joined networks about said pivoting means to thereby vary the ratio of the power delivered to said loads i'rom said source. v

2. The system of claim 1 in which a portion of each-conductor 01 said joined networksis curved away from said transmission line, thus permitting said networks to be selectively rocked into closer physical relationship with said line to thereby increase the ratio of the power delivered to. said loads.

3. Asource of power, a pair of loads, a transmission line connecting said loads and shortcircuited at a point intermediate its ends, a pair of Joined network sections, one section being coupled to said transmission line'on each side of the short-circuited point in said line, means connecting both said network sections to said source of power, and means for simultaneously adjusting the position of both said network sections with respect to said transmission line to vary the relative coupling between said sections and said line. r

4. The combination of claim 3. in which the said adjusting. means comprises pivoting meansat the-junction between said network sections.

- andvmeans for rocking said sections about said 'ity one to the pther should preferably be main- I C, D, it should be noted that under these conditions the input impedance Zo of line 2|, 22 will vary with'each position of crank it.

While I have described above the principles of my invention in connection 'with a specific system, it is to be clearly understood that this description is made only by way of example and not as a limitation on the scope of my invention as set forth in the objects of my invention and the accompanying claims; For instance, the network sections '0, D may if desired be pivoted independentlyat points i5, It so that each may be rotated without causing rotationof the other. By means of this construction a desired degree of power transfer to one of the loads R1, R2 may be maintained while the power transfer to the remaining load altered. Such mode of operation is also useful in obtaining a vernier adjustment of either network section without disturbing the coupling of the other. A

What is claimed is:

-l. In a system for coupling a source of highfrequency power to a pair of loads, a transmis== sion line connecting the loads, said transmission line consisting of two conductors in parpivoting means.

5. A system for coupling a plurality of loads to 2. single source of high-frequency power, comprising a transmission line formed of two spacedapart conductors connected to each load, said transmission line having a common linear portion, a short-circuit in said transmission line at substantially the mid-point in said linear portion thereof, a pair of network conductors lying above the linear portion of said transmission line and in spaced-apart parallel relation therewith, said network conductors being short-circuited at each end thereof, connections between the mid-points of said network conductors, respectively, and said source of powenthe connected points of said nettwork conductors lying above the short-circuited point in said transmission line, and means for' rotating said network conductors as a unit about said connected Points. e

6. In a system for coupling a plurality of loads to a single source of high-frequency power, a plurality of transmission lines connecting said loads and having a common portion, a. pair of networks coupled to the common portion of said transmission iines, means connecting both of said networks to saidsource of power, means shortcircuiting the common portion of said transmission line so that said networks are coupled to said common portion on opposite sides of the short-circuited point therein, and means for varying the coupling between each network and its associated part of said common portion.

'7. In a system for coupling a source of highfrequency power to a pair of loads, a transmission line of the order of a half-wavelength of the power produced by said source connecting the loads, said transmission line consisting of two conductors in spaced-apart parallel relation and short-circuited at the mid-point thereof so that each portion of said line is electrically equivalent to a quarter-wavelength, a pair of network sections, each section comprising a pair of network conductors in parallel relation and opencircuited at one end and short-circuited at the other end, the electrical length of each conductor of each section being of the order of a quarterwavelength of the power produced by said source, means for rigidly joining the open ends of the respective conductors of said networks so that the said respective conductors are in substantially linear relation, said rigidly joined networks lying above said transmission line in parallel spaced relation therewith so that the junction between said networks is adjacent the point at which said line is short-circuited, means connecting the junction of said networks to said source of power, means for pivoting said joined networks at said junction point thereoi,'and means for selectively rocking said joined networks about said pivoting means to thereby vary the ratio of the power delivered to said loads from said source.

8. The system of claim 7 in which a portion of each conductor of said joined networks is curved away from said transmission line, thus permitting said networks to be selectively rocked into closer physical relationship with said line to thereby inand having a common portion extending for a distance electrically equivalent to a half-wavelength of the power produced by said source, a pair of networks coupled to the common portion of said transmission lines, each 01' said networks being electrically equivalent in length to a quarter-wavelength of the power produced by said source, means connecting both 01 said networks to said source of power, means short-circuitin the common portion of said transmission line at the mid-point thereof so that the said networks are coupled to said common portion on opposite sides of the short-cirouited mid-point thereof, and means for varying the coupling between each network and its associated part of said common portion. 10. A source of power, a pair of loads, a transmission line connected to said loads and shortcircuited at a point intermediate its ends, a pair of connected network sections, one section being coupled to said transmission line on each side of the short-circuited point in said line, means connecting both said network sections to said source of power, and means for adjusting the relative positions of said network sections with respect to said transmission line to vary the relative coupling between said sections and said line.

MORTON FUCHS. 

